1. Field of the Invention
The present invention relates to a medical device for performing thoracentesis, and more particularly to a thoracentesis device which is used for the removal of fluid from the pleural cavity. More specifically, the present invention relates to a thoracentesis device having a hypersensitive dual spring detection mechanism that greatly reduces the possibility of lung puncture or laceration by the device during thoracentesis.
2. Prior Art
Thoracentesis involves the removal or evacuation of fluid from the pleural cavity between the lungs and the chest wall of a patient who has sustained some kind of trauma to the pleural cavity area. Evacuation of fluid from the pleural cavity is a necessary procedure in order to allow the lungs to expand properly and promote proper convalescence. During a prior art thoracentesis procedure, a user makes an incision through the chest wall and inserts a catheter or other tubular member through the incision and into the pleural cavity. The proximal end of the catheter is then connected to a negative pressure source, e.g. luer tip syringe, and fluid which includes blood, air and other body secretions may be evacuated from the pleural cavity through the catheter by operation of the syringe.
Medical devices used to remove fluid from the pleural cavity during a thoracentesis procedure are well known in the art. A typical prior art device for performing thoracentesis is disclosed in U.S. Pat. No. 4,447,235 to Clarke entitled xe2x80x9cThoracentesis Devicexe2x80x9d which discloses a flexible catheter having a distal end and a proximal end, a means defining an elongated conduit connected to the proximal end of the catheter and in line therewith, and a hollow needle having a sharpened distal end adapted to penetrate the chest cavity. However, the drawback of the Clarke device is that an inadvertent puncture of an internal body organ by the sharpened distal end of the catheter could possibly occur during insertion of the device through the chest wall since there is no provision for indicating whether the sharp distal end of the device has made contact with the lungs, or other body organ, once the sharpened distal end enters the pleural cavity.
Other medical devices, such as verress-type needle device, used for pneumoperitoneum also require a means for detecting whether the sharpened distal end of the device has made contact with an internal body organ when insufflating the abdominal cavity. A typical Verress-type needle device is disclosed in U.S. Pat. No. 5,256,148 to Smith et al., entitled xe2x80x9cVerress Needle with Enhanced Acoustical Meansxe2x80x9d which shows a single spring-loaded, blunt tipped inner needle slidably contained within a larger diameter piercing outer needle fixedly attached to the handle of the device. In operation, the outer needle of the Verress-type needle device is used to penetrate completely through the abdominal and stomach walls and enter the stomach. As the outer needle penetrates the stomach, the resistance applied against the single spring loaded inner needle causes the inner needle to withdraw inside the conduit of the outer needle such that the sharp end of the outer needle is exposed and extends outwardly beyond the blunt tip inner needle. Once the outer needle completely penetrates the stomach wall and enters the stomach, the resistance against the end of the inner needle applied by the stomach wall is removed so that the single spring force applied to the inner needle causes the blunt tip distal end thereof to move forwardly to a fully extended position beyond the sharp distal end of the outer needle. The Smith et al. device is also provided with a detection means for visually indicating to the user whether the fully extended blunt tip distal end of the inner needle has made contact with an internal body organ after insertion into the stomach. The detection means of the Smith et al. device comprises a single spring arrangement wherein the proximal end of the inner needle disposed inside the housing of the device is spring loaded and operatively connected to a detection means such that a visual indication is given to the user that contact has been made by the blunt tip distal end of the inner needle. The detection means also features two opposite colored bands that are viewed through a window made in the handle of the device. One of the colored bands indicates that the blunt tip distal end of the inner needle is in a fully extended position outwardly beyond the sharp tip of the outer needle, thereby visually indicating to the user that the distal end of the device has not made physical contact with an internal body organ after entry into the stomach. The opposite colored band indicates that the blunt tip distal end of the inner needle has made contact with a body organ and has been retracted into the conduit of the outer needle so that the sharpened tip of the outer needle is exposed. These opposite colored bands provide a visual stimulus to the user as to whether contact is being made by the blunt tip distal end of the device with an internal body organ, thus inadvertent puncture or lacerations of other body organs can be prevented. However, the detection means of the Smith et al. device could be improved even further when applied to thoracentesis or other invasive procedures. The single spring arrangement used to visually indicate the position of the distal end of the device could be improved to provide enhanced detection sensitivity to indicate whether contact has been made with the lungs or other internal body organs.
Therefore, there appears a need in the art for a medical device which includes an indication means that provides improved sensitivity as to the position of the blunt tip distal end of the inner needle relative to the sharpened outer needle of the device.
In brief summary, the present invention overcomes and substantially alleviates the deficiencies in the prior art by providing a thoracentesis device having a hypersensitive dual spring detection mechanism that provides quick and immediate visual indication to the user of when the blunt tip distal end of the inner needle of the device has made contact with a body organ, thereby preventing puncture or laceration of the lung area during thoracentesis. The thoracentesis device of the present invention comprises an outer needle fixedly attached at its proximal end to a handle and a sharp distal end adapted for penetrating the chest wall of a patient. The sharp distal end of the outer needle includes an opening in communication with a first conduit formed along the longitudinal axis of the outer needle. Slidably disposed inside the first conduit is a smaller diameter inner needle having a spring-loaded proximal end slidably engaged inside the handle and a blunt tip distal end which, in its fully extended position, extends a short distance outwardly beyond the sharp distal end of the outer needle. A plurality of radial ports are formed around the blunt tip distal end of the inner needle with each port in communication with a second conduit that extends longitudinally through the inner needle and opens into a cavity formed inside the handle. The second conduit of the inner needle provides a means for evacuating fluid via a fluid pathway established through the second conduit and cavity of the thoracentesis device.
The blunt tip distal end of the inner needle is maintained in its fully extended position due to its operative engagement with a large spring housed in the handle which applies a distal spring force along the longitudinal axis of the inner needle. The inner needle is also operatively engaged with a small spring which applies a smaller proximal spring force in direct opposition to the distal spring force applied by the large spring. The large spring and a small spring form a part of the dual spring detection mechanism of the present invention which provides an immediate visual indication that the blunt tip distal end of the inner needle has made contact with an internal organ, such as the lungs, while the thoracentesis device is operating inside the pleural cavity of a patient. When properly assembled, the detection mechanism has a dual spring arrangement operatively connected to an indicator arrangement comprising positive and negative indicators. The positive indicator is attached to a portion of the blunt tip inner needle housed in the cavity of the handle so that longitudinal movement by the spring-loaded inner needle necessarily moves the positive indicator relative to the stationary negative indicator which is nested and hidden inside the positive indicator. A cavity is formed at the distal end of the positive indicator for housing and completely masking the negative indicator from view through the transparent housing of the handle when the inner needle is in a fully extended position.
The dual spring arrangement according to the present invention is designed so that the large spring is in a minimum compressed state and the small spring is in a maximum compressed state when the blunt tip distal end is maintained in its fully extended position. In operation, when the blunt tip distal end makes contact with a body organ, e.g. the lungs, after insertion of the thoracentesis device through the patient""s chest wall, the proximal contact force applied by the lungs to the blunt tip distal end of the inner needle in combination with the proximal spring force generated by the small spring, more quickly overcomes the distal spring force applied by the large spring at a reduced organ contact force than that required of prior art single spring arrangements. In other words, the addition of the proximal spring applied by the small spring requires a much smaller contact force to be applied by the contacted organ in order to more quickly visually alert the user that the inner needle is being withdrawn and the sharp distal end of the outer needle is being exposed. As the combined proximal forces applied by the small spring and contacted body organ become greater than the single distal spring force applied by the large spring, the positive indicator is made to move relative to the stationary negative indicator which exposes the negative indicator to view from its nested position inside the positive indicator and visually alerts the user that contact has been made by the blunt tip distal end of the inner needle. Accordingly, the addition of a second spring provides added detection sensitivity to the slightest contact made by the blunt tip distal end of the inner needle which better avoids inadvertent punctures or lacerations by the sharp distal end of the outer needle.
It will be appreciated that the dual spring arrangement of the present invention provides enhanced detection sensitivity by the thoracentesis device to the slightest contact made by the blunt tip distal end of the inner needle with a body organ. In the absence of the small spring providing a counterforce against the large spring, a much greater contact force by the body organ against the blunt tip distal end would be required to detect and alert the user that an internal organ was contacted. This lessened sensitivity by the single spring detection mechanism could cause possible inadvertent puncture or laceration of the lung wall since the user would be unaware that the blunt tip distal end had made sufficient contact with the body organ and exposed the sharp distal end of the thoracentesis device to the body organ.
The thoracentesis device of the present invention further comprises a sleeve member disposed in the cavity of the handle. The sleeve member includes distal and proximal bores with the distal bore housing the large spring therein as well as a portion of the positive indicator. The sleeve member also includes an axial opening formed through an internal shoulder which communicates with both proximal and distal bores and establishes a fluid pathway which extends from the radial ports of the inner needle to an opening formed at the proximal end of the handle. The proximal bore communicates with a one-way valve for preventing the reflux of evacuated fluid back through the thoracentesis device. Finally, the opening may be connected to a negative pressure device, e.g. a luer-tipped syringe, for manually evacuating fluid from the pleural cavity and out through the thoracentesis device.
Accordingly, a primary object of the present invention is to provide a medical device which is operable to reduce the possibility of inadvertent puncture or laceration of the lung or other body organ by the device.
Another object of the present invention is to provide a hypersensitive detection means for quickly indicating contact of a body organ by the distal end of the medical device to the user.
A further object of the present invention is to provide a visual indication means that may be viewed at any angle through the handle of the medical device.
Another further object of the present invention is to provide a dual spring arrangement operatively connected to a visual indication means for enhanced detection of an internal body organ by the medical device.
These and other objects of the present invention are realized in the preferred embodiment of the present invention, described by way of example and not by way of limitation, which provides for a medical device having a hypersensitive detection means for indicating contact of the distal end of the device with a body organ.
Additional objects, advantages and novel features of the invention will be set forth in the description which follows, and will become apparent to those skilled in the art upon examination of the following more detailed description and drawings in which like elements of the invention are similarly numbered throughout.